Patent application title: Flat Drop Cable

Abstract:

The present disclosure relates to a fiber optic cable including an outer
jacket having an elongated transverse cross-sectional profile defining a
major axis and a minor axis. The transverse cross-sectional profile has a
maximum width that extends along the major axis and a maximum thickness
that extends along the minor axis. The maximum width of the transverse
cross-sectional profile is longer than the maximum thickness of the
transverse cross-sectional profile. The outer jacket also defines first
and second separate passages that extend through the outer jacket along a
lengthwise axis of the outer jacket. The second passage has a transverse
cross-sectional profile that is elongated in an orientation extending
along the major axis of the outer jacket. The fiber optic cable also
includes a plurality of optical fibers positioned within the first
passage a tensile strength member positioned within the second passage.
The tensile strength member has a highly flexible construction and a
transverse cross-sectional profile that is elongated in the orientation
extending along the major axis.

Claims:

1. A fiber optic cable comprising:an outer jacket having an elongated
transverse cross-sectional profile defining a major axis and a minor
axis, the transverse cross-sectional profile having a maximum width that
extends along the major axis and a maximum thickness that extends along
the minor axis, the maximum width of the transverse cross-sectional
profile being longer than the maximum thickness of the transverse
cross-sectional profile, the outer jacket also defining first and second
separate passages that extend through the outer jacket along a lengthwise
axis of the outer jacket, the second passage having a transverse
cross-sectional profile that is elongated in an orientation extending
along the major axis of the outer jacket;a plurality of optical fibers
positioned within the first passage; anda tensile strength member
positioned within the second passage, the tensile strength member having
a transverse cross-sectional profile that is elongated in the orientation
extending along the major axis, the tensile strength member being
sufficiently flexible to be wrapped in a circle having a 10 millimeter
inner diameter for one hour without undergoing meaningful deterioration
in tensile strength.

2. The fiber optic cable of claim 1, wherein the first passage has a
generally round transverse cross-sectional profile.

3. The fiber optic cable of claim 1, wherein the first passage is not
lines with a buffer tube.

4. The fiber optic cable of claim 3, wherein two separating members are
contrahelically served about the optical fibers to separate the optical
fibers from a portion of the outer jacket that defines the first passage.

5. The fiber optic cable of claim 1, wherein the strength member is bonded
to the outer jacket.

6. The fiber optic cable of claim 5, wherein the strength member is bonded
to the outer jacket with an adhesive material.

9. The fiber optic cable of claim 1, wherein the first and second passages
are aligned along the major axis.

10. The fiber optic cable of claim 9, wherein the tensile strength member
provides asymmetrical tensile reinforcement to the fiber optic cable
about the minor axis.

11. The fiber optic cable of claim 1, wherein the tensile strength member
does not provide meaningful compressive reinforcement to the outer jacket
in an orientation that extends along the lengthwise axis.

12. The fiber optic cable of claim 1, wherein the tensile strength member
can carry a tensile load of at least 300 pounds.

13. The fiber optic cable of claim 1, wherein the tensile strength member
can carry a tensile load of at least 150 pounds.

14. The fiber optic cable of claim 12, wherein the tensile strength member
retains at least 95 percent of its pre-wrapped tensile strength after
having been wrapped in the circle having the 10 millimeter inner diameter
for one hour.

15. The fiber optic cable of claim 13, wherein the tensile strength member
retains at least 95 percent of its pre-wrapped tensile strength after
having been wrapped in the circle having the 10 millimeter inner diameter
for one hour.

16. The fiber optic cable of claim 1, wherein the outer jacket includes a
polymeric base material and a shrinkage reduction material disposed
within the polymeric base material.

18. The fiber optic cable of claim 1, wherein the first and second
passages are aligned along the major axis, wherein the first passage has
a circular transverse cross-sectional profile, wherein the first passage
is not lined with a buffer tube, wherein the tensile strength member is
bonded to the outer jacket, and wherein the outer jacket includes a
polymeric base material and a liquid crystal polymer disposed within the
base material.

19. The fiber optic cable of claim 1, wherein when the outer jacket is
viewed in transverse cross-section, the outer jacket has a first portion
in which the first passage is defined and a second portion in which the
second passage is defined, wherein the first portion defines a first
thickness and the second portion defines a second thickness, wherein the
second thickness is the maximum thickness of the outer jacket, and
wherein the second thickness is thicker than the first thickness.

20. The fiber optic cable of claim 19, wherein the first thickness
coincides with a center of the first passage and the second thickness
coincides with a center of the second passage.

21. A fiber optic cable comprising:an outer jacket having an elongated
transverse cross-sectional profile defining a major axis and a minor
axis, the transverse cross-sectional profile having a maximum width that
extends along the major axis and a maximum thickness that extends along
the minor axis, the maximum width of the transverse cross-sectional
profile being longer than the maximum thickness of the transverse
cross-sectional profile, the outer jacket also defining first and second
separate passages that extend through the outer jacket along a lengthwise
axis of the outer jacket, the second passage having a transverse
cross-sectional profile that is elongated in an orientation extending
along the major axis of the outer jacket;a plurality of optical fibers
positioned within the first passage; anda tensile strength member
positioned within the second passage, the tensile strength member having
a transverse cross-sectional profile that is elongated in the orientation
extending along the major axis, the tensile strength member not providing
meaningful compressive reinforcement to the outer jacket in an
orientation that extends along the lengthwise axis.

[0002]A fiber optic cable typically includes: (1) an optical fiber; (2) a
buffer layer that surrounds the optical fiber; (3) a plurality of
reinforcing members loosely surrounding the buffer layer; and (4) an
outer jacket. Optical fibers function to carry optical signals. A typical
optical fiber includes an inner core surrounded by a cladding that is
protected by a coating. The buffer layer functions to surround and
protect the coated optical fibers. Reinforcing members add mechanical
reinforcement to fiber optic cables to protect the internal optical
fibers against stresses applied to the cables during installation and
thereafter. Outer jackets also provide protection against chemical
damage.

[0003]Drop cables used in fiber optic networks can be constructed having a
jacket with a flat transverse profile. Such cables typically include a
central buffer tube containing a plurality of optical fibers, and
reinforcing members such as rods made of glass reinforced epoxy embedded
in the jacket on opposite sides of the buffer tube. U.S. Pat. No.
6,542,674 discloses a drop cable of a type described above. Flat drop
cables of the type described above are designed to be quite robust.
However, as a result of such cables being strong and robust, such cables
are typically quite stiff, inflexible and difficult to handle.
Additionally, such cables can be expensive to manufacture.

SUMMARY

[0004]The present disclosure relates to a fiber optic cable including an
outer jacket having an elongated transverse cross-sectional profile
defining a major axis and a minor axis. The transverse cross-sectional
profile has a maximum width that extends along the major axis and a
maximum thickness that extends along the minor axis. The maximum width of
the transverse cross-sectional profile is longer than the maximum
thickness of the transverse cross-sectional profile. The outer jacket
also defines first and second separate passages that extend through the
outer jacket along a lengthwise axis of the outer jacket. The second
passage has a transverse cross-sectional profile that is elongated in an
orientation extending along the major axis of the outer jacket. The fiber
optic cable also includes a plurality of optical fibers positioned within
the first passage a tensile strength member positioned within the second
passage. The tensile strength member has a highly flexible construction
and a transverse cross-sectional profile that is elongated in the
orientation extending along the major axis.

[0005]A variety of additional aspects will be set forth in the description
that follows. These aspects can relate to individual features and to
combinations of features. It is to be understood that both the foregoing
general description and the following detailed description are exemplary
and explanatory only and are not restricted of the broad concepts upon
which the embodiments disclosed herein are based.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a transverse cross-sectional view of a fiber optic cable
having features that are examples of aspects in accordance with the
principles of the present disclosure.

[0007]FIG. 2 is a perspective view of an optical fiber suitable for use in
the fiber optic cable of FIG. 1.

[0008]FIG. 3 is a transverse cross-sectional view of another fiber optic
cable having features that are examples of aspects in accordance with the
principles of the present disclosure.

[0009]FIG. 4 is a plan view of another fiber optic cable in accordance
with the principles of the present disclosure.

[0010]FIG. 5 is a transverse cross-sectional view of the fiber optic cable
of FIG. 4 taken along section line 5-5.

[0011]FIG. 6 is a perspective view of contrahelical separating members
that can be used to group together the optical fibers of the fiber optic
cable of FIGS. 4 and 5 and can also be used to separate the optical
fibers from the cable jacket material enclosing the fibers.

[0012]FIG. 7 is a plan view of a further fiber optic cable in accordance
with the principles of the present disclosure.

[0013]FIG. 8 is a transverse cross-sectional view of the fiber optic cable
of FIG. 7 taken along section line 8-8.

[0014]FIG. 9 is an end view of a test system for testing the flexibility
of the strength members of the fiber optic cables of FIGS. 4, 5, 7 and 8.

[0016]FIG. 11 is a top plan view of still another fiber optic cable in
accordance with the principles of the present disclosure.

[0017]FIG. 12 is a transverse cross-sectional view of the fiber optic
cable of FIG. 11 taken along section line 12-12.

DETAILED DESCRIPTION

[0018]FIG. 1 shows a fiber optic cable 10 in accordance with the
principles of the present disclosure. The fiber optic cable 10 includes
at least one optical fiber 12 contained within a buffer tube 14. An outer
jacket 16 surrounds the buffer tube 14. A reinforcing member 18 is
embedded in the outer jacket 16 to provide the fiber optic cable 10 with
axial reinforcement.

[0019]Referring still to FIG. 1, the outer jacket 16 has a non-circular
outer profile. For example, as shown at FIG. 1, when viewed in transverse
cross-section, the outer profile of the outer jacket 16 has a flat
generally obround or rectangular shape. The outer jacket 16 is longer
along a major axis 20 than along a minor axis 21. The major and minor
axes 20, 21 are perpendicular to one another and intersect at a center 27
of the outer jacket 16.

[0020]Referring still to FIG. 1, the outer jacket 16 defines a single
fiber passage 23 in which the buffer tube 14 is located. As illustrated
in the example of FIG. 1, the fiber passage 23 may have a circular
profile. The fiber passage 23 has a center 25 that is offset from the
center 27 of the outer jacket 16.

[0021]The outer jacket 16 also defines a single reinforcing member passage
28 having a center 30 that is also offset from the center 27 of the outer
jacket 16. The center 27 of the outer jacket 16 is the geometric center
of the outer profile of the outer jacket 16. As illustrated in the
example of FIG. 1, the reinforcing member passage 28 may have a circular
profile. The center 25 of the fiber passage 23 is located at an opposite
side of the minor axis 21 as compared to the center 30 of the reinforcing
member passage 28. Consequently, the outer jacket 16 is thicker along the
minor axis 21 through the center 27 of the outer jacket 16 than along an
axis parallel to the minor axis 21 through the center 25 of the fiber
passage 23 or an axis parallel to the minor axis 21 through the center 30
of the reinforcing member passage 28.

[0022]Furthermore, because the center 25 of the fiber passage 23 is
located at an opposite side of the minor axis 21 as compared to the
center 30 of the reinforcing member passage 28, the outer jacket 16
contains no cavities along the minor axis 21 through the center 27 of the
outer jacket 16. Because the outer jacket 16 contains no cavities along
the minor axis 21 through the center 27 of the outer jacket 16, the outer
jacket 16 does not significantly compress the fiber passage 23 or crush
the optical fibers 12 when the fiber optic cable 10 is clamped during
installation of the fiber optic cable 10. Rather, the portion of the
outer jacket 16 along the minor axis 21 through the center 27 of the
outer jacket 16 serves to support the fiber passage 23 against
compression forces exerted by clamping during installation.

[0023]It will be appreciated that the outer jacket 16 can be made of any
number of different types of polymeric materials. In one embodiment, the
outer jacket 16 is made of a medium density ultra-high molecular weight
polyethylene.

[0024]The buffer tube 14 can also be made of any number of different
polymeric materials. For example, the buffer tube 14 can be made of a
polymeric material such as polyvinyl chloride (PVC). Other polymeric
materials (e.g., polyethylenes, polyurethanes, polypropylenes,
polyvinylidene fluorides, ethylene vinyl acetate, nylon, polyester, or
other materials) may also be used.

[0025]In certain embodiments, the reinforcing member 18 can include a
single reinforcing rod positioned within the reinforcing member passage
28 of the outer jacket 16. In certain embodiments, the single rod can be
made of glass fibers imbedded within a resin such as epoxy.

[0026]Referring now to FIGS. 1 and 2, one or more optical fibers 12 can be
positioned within the buffer tube 14. In a preferred embodiment, the
buffer tube 14 contains at least twelve optical fibers 12. It will be
appreciated that the optical fibers 12 can have any number of different
types of configurations. In one embodiment, the optical fiber 12 includes
a core 32. The core 32 is made of a glass material, such as a
silica-based material, having an index of refraction. In the subject
embodiment, the core 32 has an outer diameter D1 of less than or
equal to about 10 μm.

[0027]The core 32 of each optical fiber 12 is surrounded by a first
cladding layer 34 that is also made of a glass material, such as a silica
based-material. The first cladding layer 34 has an index of refraction
that is less than the index of refraction of the core 32. This difference
between the index of refraction of the first cladding layer 34 and the
index of refraction of the core 32 allows an optical signal that is
transmitted through the optical fiber 12 to be confined to the core 32.

[0028]A trench layer 36 surrounds the first cladding layer 34. The trench
layer 36 has an index of refraction that is less than the index of
refraction of the first cladding layer 34. In the subject embodiment, the
trench layer 36 is immediately adjacent to the first cladding layer 34.

[0029]A second cladding layer 38 surrounds the trench layer 36. The second
cladding layer 38 has an index of refraction. In the subject embodiment,
the index of refraction of the second cladding layer 38 is about equal to
the index of refraction of the first cladding layer 34. The second
cladding layer 38 is immediately adjacent to the trench layer 36. In the
subject embodiment, the second cladding layer 38 has an outer diameter
D2 of less than or equal to 125 μm.

[0030]A coating, generally designated 40, surrounds the second cladding
layer 38. The coating 40 includes an inner layer 42 and an outer layer
44. In the subject embodiment, the inner layer 42 of the coating 40 is
immediately adjacent to the second cladding layer 38 such that the inner
layer 42 surrounds the second cladding layer 38. The inner layer 42 is a
polymeric material (e.g., polyvinyl chloride, polyethylenes,
polyurethanes, polypropylenes, polyvinylidene fluorides, ethylene vinyl
acetate, nylon, polyester, or other materials) having a low modulus of
elasticity. The low modulus of elasticity of the inner layer 42 functions
to protect the optical fiber 12 from microbending.

[0031]The outer layer 44 of the coating 40 is a polymeric material having
a higher modulus of elasticity than the inner layer 42. In the subject
embodiment, the outer layer 44 of the coating 40 is immediately adjacent
to the inner layer 42 such that the outer layer 44 surrounds the inner
layer 42. The higher modulus of elasticity of the outer layer 44
functions to mechanically protect and retain the shape of optical fiber
12 during handling. In the subject embodiment, the outer layer 44 defines
an outer diameter D3 of less than or equal to 500 μm. In another
embodiment, the outer layer 44 has an outer diameter D3 of less than
or equal to 250 μm.

[0032]In the subject embodiment, the optical fiber 12 is manufactured to
reduce the sensitivity of the optical fiber 12 to micro or macro-bending
(hereinafter referred to as "bend-insensitive"). An exemplary bend
insensitive optical fiber has been described in U.S. Pat. Application
Publication Nos. 2007/0127878 and 2007/0280615 that are hereby
incorporated by reference in their entirety. An exemplary
bend-insensitive optical fiber is commercially available from Draka
Comteq under the name BendBright XS.

[0033]Because the fiber optic cable 10 is reinforced by a single
reinforcing member 18 that is offset from the center 27 of the outer
jacket 16, the fiber optic cable 10 is provided with an asymmetric
reinforcing configuration.

[0034]FIG. 3 shows another fiber optic cable 10' in accordance with the
principles of the present disclosure. The fiber optic cable 10' has the
same construction as the fiber optic cable 10 except the buffer tube 14
has been eliminated. In this design, the optical fibers 12 are positioned
directly within the fiber passage 23 of the outer jacket 16 without any
intermediate buffer tubes. In this manner, the portion of the outer
jacket 16 defining the fiber passage 23 functions as a buffer tube for
containing the optical fibers.

[0035]It will be appreciated that the cables of FIGS. 1 and 3 can be used
as drop cables in a fiber optic network. For example, the fiber optic
cables 10, 10' can be used as drop cables in fiber optic networks such as
the networks disclosed in U.S. Provisional Patent Application Ser. No.
61/098,494, entitled "Methods and Systems for Distributing Fiber Optic
Telecommunications Services to a Local Area," filed on Sep. 19, 2008 and
hereby incorporated by reference in its entirety.

[0036]FIGS. 4 and 5 depict another fiber optic cable 100 in accordance
with the principles of the present disclosure. Generally, the cable 100
includes an outer jacket 102 defining first and second generally parallel
passages 104, 106. The cable 100 also includes a plurality of bend
insensitive fibers 12 positioned within the first passage 104 and a
strength member 107 (i.e., a tensile reinforcing member) positioned
within the second passage 106. Such a construction allows the cable 100
to be readily used for applications in which drop cables are normally
used and also allows the cable 100 to be wrapped around a cable storage
spool having a relatively small diameter without damaging the cable 100.

[0037]Referring to FIG. 5, the cable 100 has an elongated transverse
cross-sectional profile (e.g., a flattened cross-sectional profile, an
oblong cross-sectional profile, an obround cross-sectional profile, etc.)
defined by the outer jacket 102. The cable 100 defines a major axis 108
and a minor axis 110. A width W1 of the outer jacket 102 extends along
the major axis 108 and a thickness T1 of the outer jacket 102 extends
along the minor axis 110. The width W1 is longer than the thickness T1.
In certain embodiments, the width W1 is at least 50% longer than the
thickness. As depicted in FIG. 5, the width W1 is a maximum width of the
outer jacket 102 and the thickness T1 is a maximum thickness of the outer
jacket 102.

[0038]In the depicted embodiment of FIG. 5, the transverse cross-sectional
profile defined by the outer jacket 102 of FIG. 5 is generally
rectangular with rounded ends. The major axis 108 and the minor axis 110
intersect perpendicularly at a lengthwise axis 112 of the cable 100.

[0039]The construction of the cable 100 allows the cable 100 to be bent
more easily along a plane P1 that coincides with the minor axis 110 than
along a plane P2 that coincides with the major axis 108. Thus, when the
cable 100 is wrapped around a spool or guide, the cable 100 is preferably
bent along the plane P1.

[0040]As indicated above, the outer jacket 102 defines the elongate
transverse cross-sectional profile of the cable 100. The first and second
passages 104, 106 are aligned along the major axis 108 of the cable 100.
The first passage 104 has a generally circular transverse cross-sectional
profile while the second passage 106 has an elongate transverse
cross-sectional profile. For example, the second passage 106 is elongated
in an orientation that extends along the major axis 108 of the cable 100.
In the depicted embodiment, the first passage 104 is not lined with a
buffer tube. However, in other embodiments, a buffer tube may be used.

[0041]It will be appreciated that the outer jacket 102 of the cable 100
can be shaped through an extrusion process and can be made by any number
of different types of polymeric materials. In certain embodiments, the
outer jacket 102 can have a construction the resists post-extrusion
shrinkage of the outer jacket 102. For example, the outer jacket 102 can
include a shrinkage reduction material disposed within a polymeric base
material (e.g., polyethylene). U.S. Pat. No. 7,379,642, which is hereby
incorporated by reference in its entirety, describes an exemplary use of
shrinkage reduction material within the base material of a fiber optic
cable jacket.

[0042]In one embodiment, the shrinkage reduction material is a liquid
crystal polymer (LCP). Examples of liquid crystal polymers suitable for
use in fiber-optic cables are described in U.S. Pat. Nos. 3,911,041;
4,067,852; 4,083,829; 4,130,545; 4,161,470; 4,318,842; and 4,468,364
which are hereby incorporated by reference in their entireties. To
promote flexibility of the cable 100, the concentration of shrinkage
material (e.g. LCP) is relatively small as compared to the base material.
In one embodiment, and by way of example only, the shrinkage reduction
material constitutes less than about 10% of the total weight of the outer
jacket 102. In another embodiment, and by way of example only, the
shrinkage reduction material constitutes less than about 5% of the total
weight of the outer jacket 102. In another embodiment, the shrinkage
reduction material constitutes less than about 2% of the total weight of
the outer jacket 102. In another embodiment, shrinkage reduction material
constitutes less than about 1.9%, less than about 1.8%, less than 1.7%,
less than about 1.6%, less than about 1.5%, less than about 1.4%, less
than about 1.3%, less than about 1.2%, less than about 1.1%, or less than
about 1.0% of the total weight of the outer jacket 102.

[0043]Example base materials for the outer jacket 102 include low-smoke
zero halogen materials such as low-smoke zero halogen polyolefin and
polycarbon. In other embodiments, the base material can include thermal
plastic materials such as polyethylene, polypropylene,
ethylene-propylene, copolymers, polystyrene and styrene copolymers,
polyvinyl chloride, polyamide (nylon), polyesters such as polyethylene
terephthalate, polyetheretherketone, polyphenylene sulfide,
polyetherimide, polybutylene terephthalate, as well as other plastic
materials. In still other embodiments, the outer jacket 102 can be made
of low density, medium density or high density polyethylene materials.
Such polyethylene materials can include low density, medium density or
high density ultra-high molecular weight polyethylene materials.

[0044]The first passage 104 of the outer jacket 102 is sized to receive
one or more of the bend insensitive fibers 12. The bend insensitive
fibers are preferably unbuffered and in certain embodiments have outer
diameters in the range of 230-270 μm. In one embodiment, the first
passage 104 is sized to receive at least 12 of the bend insensitive
fibers 12. When the fibers 12 are positioned within the first passage
104, it is preferred for the fibers 12 to occupy less than 60% of the
total transverse cross-sectional area defined by the first passage 104.

[0045]It is preferred for the first passage 104 to be dry and not to be
filled with a water-blocking gel. Instead, to prevent water from
migrating along the first passage 104, structures such water-swellable
fibers, water-swellable tape, or water-swellable yarn can be provided
within the passage 104 along with the fibers 12. However, in certain
embodiments water-blocking gel may be used.

[0046]The strength member 107 of the cable 100 preferably has a transverse
cross-sectional profile that matches the transverse cross-sectional
profile of the second passage 106. As shown at FIG. 5, the strength
member 107 has a transverse cross-sectional width W2 that is greater than
a transverse cross-sectional thickness T2 of the strength member 107. The
width W2 extends along the major axis 108 of the cable while the
thickness T2 extends along the minor axis 110 of the cable 100. In the
depicted embodiment, the thickness T2 is bisected by the major axis 108.
In certain embodiments, the width W2 of the strength member 107 is at
least 50% longer than the thickness T2, or the width W2 of the strength
member 107 is at least 75% longer than the thickness T2, or the width W2
of the strength member 107 is at least 100% longer than the thickness T2,
or the width W2 of the strength member 107 is at least 200% longer than
the thickness T2, or the width W2 of the strength member 107 is at least
300% longer than the thickness T2, or the width W2 of the strength member
107 is at least 400% longer than the thickness T2. As depicted in FIG. 5,
the width W2 is a maximum width of the strength member 107 and the
thickness T2 is a maximum thickness of the strength member 107.

[0047]In certain embodiments, the strength member 107 is bonded to the
outer jacket 102. The bonding between the strength member 107 and the
outer jacket 102 can be chemical bonding or thermal bonding. In one
embodiment, the strength member 107 may be coated with or otherwise
provided with a material having bonding characteristics (e.g., ethylene
acetate) to bond the strength member 107 to the outer jacket 102.

[0048]The strength member 107 preferably has a construction that is highly
flexible and highly strong in tension. For example, in certain
embodiments, the strength member 107 provides the vast majority of the
tensile load capacity of the cable 100. For example, in one embodiment,
the strength member 107 carries at least 95% of a 150 pound tensile load
applied to the cable 100 in a direction along the lengthwise axis 112. In
one embodiment, the strength member 107 can carry a 150 pound tensile
load applied in an orientation extending along a central longitudinal
axis of the strength member 107 without undergoing meaningful
deterioration of the tensile properties of the strength member 107. In
another embodiment, the strength member 107 can carry a 200 pound tensile
load applied in an orientation extending along the central longitudinal
axis of the strength member 107 without undergoing meaningful
deterioration in its tensile properties. In still another embodiment, the
strength member 107 can carry a 300 pound tensile load applied in an
orientation that extends along the central longitudinal axis of the
strength member 107 without experiencing meaningful deterioration of its
tensile properties.

[0049]It is preferred for the strength member 107 to be able to provide
the tensile strengths described above while concurrently being highly
flexible. In determining the tensile strength of the cable 102, tensile
load is applied to the cable 102 in a direction that extends along the
lengthwise axis 112 of the cable 100. Similarly, to determine the tensile
strength of the strength member 107, tensile load is applied to the
strength member 107 in a direction that extends along central
longitudinal axis 114 of the strength member 107. In one embodiment, a
strength member 107 having tensile strength characteristics as described
above also has a flexibility that allows the strength member 107 to be
wrapped at least 360 degrees around a mandrel 300 (see FIGS. 9 and 10)
having a 10 millimeter outer diameter for one hour without
undergoing/experiencing meaningful deterioration/degradation of the
tensile strength properties of the strength member 107. As shown at FIGS.
9 and 10, the 360 degree wrap is aligned generally along a single plane
P3 (i.e., the 360 degree wrap does not form a helix having an extended
axial length). In this way, the strength member 107 conforms to the outer
diameter of the mandrel and generally forms a circle having an inner
diameter of 10 millimeters. This test can be referred to as the "mandrel
wrap" test. In certain embodiments, the strength member 107 maintains at
least 95% of its pre-mandrel wrap test tensile strength after having been
subjected to the mandrel wrap test. In certain embodiments, the strength
member 107 does not "broom stick" when subjected to the mandrel wrap test
described. As used herein, the term "broom stick" means to have
reinforcing elements of the strength member visually separate from the
main body of the strength member 107. In certain embodiments, the
strength member 107 does not generate any audible cracking when exposed
to the mandrel wrap test.

[0050]In certain embodiments, the strength member 107 is formed by a
generally flat layer of reinforcing elements (e.g., fibers or yarns such
as aramid fibers or yarns) embedded or otherwise integrated within a
binder to form a flat reinforcing structure (e.g., a structure such as a
sheet-like structure, a film-like structure, or a tape-like structure).
In one example embodiment, the binder is a polymeric material such
ethylene acetate acrylite (e.g., UV-cured, etc.), silicon (e.g., RTV,
etc.), polyester films (e.g., biaxially oriented polyethylene
terephthalate polyester film, etc.), and polyisobutylene. In other
example instances, the binder may be a matrix material, an adhesive
material, a finish material, or another type of material that binds,
couples or otherwise mechanically links together reinforcing elements.

[0051]In other embodiments, the strength member 107 can have a glass
reinforced polymer (GRP) construction. The glass reinforced polymer can
include a polymer base material reinforced by a plurality of glass fibers
such as E-glass, S-glass or other types of glass fiber. The polymer used
in the glass reinforced polymer is preferably relatively soft and
flexible after curing. For example, in one embodiment, the polymer has a
Shore A hardness less than 50 after curing. In other embodiments, the
polymer has a Shore A hardness less than 46 after curing. In certain
other embodiments, the polymer has a Shore A hardness in the range of
about 34-46.

[0052]In one embodiment, the strength member 107 can have a width of about
0.085 inches and a thickness of about 0.045 inches. In another
embodiment, such a strength member may have a width of about 0.125 inches
and a thickness of about 0.030 inches. In still further embodiments, the
strength member has a thickness in the range of 0.020-0.040 inches, or in
the range of 0.010-0.040 inches, or in the range of 0.025-0.035 inches.
Of course, other dimensions could be used as well. In additional
embodiments, the strength member may have a width in the range of
0.070-0.150 inches. Of course, other sizes could be used as well.

[0053]In certain embodiments, the strength member 107 preferably does not
provide the cable 100 with meaningful resistance to compression loading
in an orientation extending along the lengthwise axis 112. For example,
in certain embodiments, the outer jacket 102 provides greater resistance
to compression than the strength member 107 in an orientation extending
along the lengthwise axis 112. Thus, in certain embodiments, the
reinforcing member 107 does not provide the cable 100 with meaningful
compressive reinforcement in an orientation that extends along the
lengthwise axis 112. Rather, resistance to shrinkage or other compression
of the cable 100 along the lengthwise axis 112 can be provided by the
outer jacket 102 itself through the provision of the shrinkage reduction
material within the base material of the outer jacket 102. In this type
of embodiment, when a compressive load is applied to the cable 100 along
the lengthwise axis 112, a vast majority of the compressive load will be
carried by the outer jacket 102 as compared to the strength member 107.

[0054]As depicted in FIG. 5, the fibers 12 are loose within the first
passage 104. In other embodiments, the fibers 12 within the first passage
104 can be surrounded and grouped together by separating members that can
separate the fibers 12 from the jacket material defining the first
passage 104. Such separating can assist in preventing the fibers 12 from
contacting the extrusion die or extrusion tip during extrusion of the
outer jacket 102 over the fibers 12. In certain embodiments, first and
second sets of separating members 120a, 120b can be contra-helically
served about the group of fibers 12. For example, in the depicted
embodiment of FIG. 6, the first set of separating members 120a is
disposed about the fibers 12 in a generally right-handed helical wrap
configuration while the second set of separating members 120b is disposed
about the optical fibers 12 in a generally left-handed helical wrap
configuration. In certain embodiments, the separating members 120a, 120b
can have helical wrap angles α less than 20 degrees or less than 15
degrees. In certain embodiments, the separating members can be yarns. In
one embodiment, the separating members are formed by aramid yarn. In
certain embodiments, water swellable material can be coated on or
otherwise incorporated into the binding members.

[0055]In the depicted embodiment of FIG. 6, the contra-helical serve of
separating members extends around the entire group of optical fibers 12.
In other embodiments, contra-helical serving can be used to divide the
fibers 12 into separate groups. For example, the fibers 12 can be
separated into three groups of 4 optical fibers 12 with contra-helical
serving provided around each of the groups of 4 fibers 12.

[0056]FIGS. 7 and 8 depict another cable 200 in accordance with the
principles of the present disclosure. The cable 200 includes many of the
same components as the as the cable 100 (e.g., the strength member 107,
the optical fibers 12, the passages 104, 106). However, the cable 200
includes an outer jacket 202 having a transverse cross-sectional profile
that has been modified to include a variable thickness (e.g., a dual
thickness) to improve the crush-resistance of the cable 200. Crush
resistance can be significant when the cable is used with a cable clamp
such as a "P-clamp."

[0057]Referring to FIG. 8, the outer jacket 202 of the cable 200 has an
elongated transverse cross-sectional profile. The cable 200 defines a
major axis 208 and a minor axis 210. A width W3 of the outer jacket 202
extends along the major axis 208 and thicknesses T3, T4 of the outer
jacket 202 extend along the minor axis 210. The thickness T3 is smaller
than the thickness T4, and the width W3 is greater than the thickness T4.
The thickness T3 is defined by a first portion 230 of the jacket 202 in
which the first passage 104 containing the optical fibers 12 is formed.
The thickness T4 is defined by a second portion 232 of the jacket 202 in
which the second passage 106 containing the strength member 107 is
formed. In the depicted embodiment, the first portion 230 is positioned
at or defines a first end 234 of the transverse cross-sectional profile
of the cable 200 and the second portion 231 is positioned at or defines
an opposite second end 236 of the transverse cross-sectional profile of
the cable 200. When viewed in transverse cross-section, the thickness T3
coincides with a center of the first passage 104 and the thickness T4
coincides with a center of the second passage 106. When the cable 200 is
compressed in an orientation that extends along the minor axis 210 (e.g.,
with a cable clamp), the increased thickness T4 provided by the second
portion 232 of the jacket 202 carries most of the compressive load
thereby preventing the first passage 104 from being deformed. In this
way, the fibers 12 within the first passage 104 are prevented from being
damaged by the compressive action.

[0058]While most of the drawings of the present disclosure show cables
having asymmetrical reinforcing configurations in which strength members
are provided only on one side of a passage containing optical fibers, it
will be appreciated that aspects of the present disclosure can be use for
other cables as well. For example, aspects of the present disclosure can
be used for a flat drop cable 400 (see FIGS. 11 and 12) having a central
passage 404 for containing fibers 12 and two passages 406 on opposite
sides of the central passage 404 for containing strength members 107.

[0059]The above specification provides examples of how certain inventive
aspects may be put into practice. It will be appreciated that the
inventive aspects can be practiced in other ways than those specifically
shown and described herein without departing from the spirit and scope of
the inventive aspects of the present disclosure.